Tissue engineering may be used to recreate tissues and organs for grafting onto patients. Engineered tissues and organs can also serve as in vitro models. A variety of tissue engineering techniques are known, including tissue in-growth, seeding of cells on artificial or biodegradable scaffolds, and collagen gels. Among them, a new method of tissue engineering, known as the “self-assembly” method, has emerged (L'Heureux et al.; Michel et al.; Pouliot et al.). In the self-assembly method, cells are induced to secrete and organise an extracellular matrix and thereby form a sheet of living tissue. The self-assembly method takes advantage of the fact that fibroblasts can produce a suitable extracellular matrix when grown in the presence of ascorbic acid. To create multi-layer tissue constructs, sheets of living tissue can be stacked upon each other, folded upon themselves, or rolled on a tubular support.
The development of tissue engineering methods to produce reconstructed tissues has focused on the optimization of morphological and histological properties of the reconstructed tissues. Most tissue engineering research has focused on optimizing techniques for growing sheets of tissue. However, in many cases, it would be desirable to make reconstructed tissue comprised of several layers of tissue and/or layers of more than one type of tissue. Multi-layer tissue constructs are thicker and therefore stronger and since multi-layer tissue constructs can comprise more than one sheet of living tissue, they can be designed to more closely resemble the tissues that they are intended to replace. However, in order to create useful multi-layer tissue constructs, it is essential to be able to fuse adjacent layers of cell tissue together so that the layers are bonded together as firmly and reliably as possible and resist separation. If these layers of tissue are not fused together well, they may separate or come apart over time, for example, during handling or in the body of a patient.
Thus, it would be desirable to have a method for preparing multi-layered engineered tissue constructs with improved fusion between adjacent layers of tissue.